Get the current date and the week of the year

java code  

1. String today = "2013-01-14";  
2. SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");  
3. Date date = null;  
4. try {  
5.     date = format.parse(today);  
6. } catch (ParseException e) {  
7.     // TODO Auto-generated catch block  
8.     e.printStackTrace();  
9. }  
10.   
11. Calendar calendar = Calendar.getInstance();  
12. calendar.setFirstDayOfWeek(Calendar.MONDAY);  
13. calendar.setTime(date);  
14.   
15. System.out.println(calendar.get(Calendar.WEEK_OF_YEAR));  

 

A somewhat complicated code is used to judge the number of weeks that the date belongs to in the current year. When looking at the Calendar class, I saw WEEK_OF_YEAR, which is very practical. But there is a small problem with the time, for example, 2010-01-03, the returned result is 2 (that is, the second week of 2010), because the United States uses Sunday as the first day of the week.

  I thought of changing the starting day of the week, setFirstDayOfWeek(int value), passed a 1, and wanted to set Monday as the first day, but it didn't work. After checking the document, it will be fine to change it to Calendar.MONDAY, but I don’t know why it is not easy to use 1, but just use Calendar.MONDAY?

  

  Supplement: I checked the "constant field value" again, and found that the value of MONDAY is not 1 at all, but 2.

  SUNDAY ：1

  WORLD ：2

  TUESDAY ：3

  WEDNESDAY ：4

  THURSDAY ： 5

  FRIDAY ： 6

  SATURDAY ：7